Echinoderms and Invertebrate Chordates One of these things is not like the others: sea squirts, sea cucumbers, chocolate chip stars, and sea biscuits

They are members of the phylum Echinodermata, except sea squirts

Objectives of the day: Describe the phylum Echinodermata, tunicates and lancelets by the features of: skeletal structure, reproduction, symmetry, unique features, body coverings and locomotion Review the five phyla we have covered to this point: sponges, cnidarians, mollusks, annelids, arthropods. Identify members from each group with critter quiz.

Phylum Echinodermata Skeletal structure: for all – endoskeleton made of plates called ossicles, –Some plates are movable others fused, – many have spines

Reproduction Varies by class Mostly sexual sperm and eggs released into water Females release fertilized eggs, Free swimming larvae

Symmetry Five part radial symmetry Except sea cucumbers they are bilateral

Unique Features Deuterstomes: in embryonic development: Anus develops first, is on top of animal Mouth is on the underside Yellow ringed anal sac on sea urchin Mouth on underside of sea star

Unique Features of all Echinoderms Water vascular system – the body cavity acts as the circulatory and respiratory system Skin gills: increase surface area for respiration and regeneration

Body Coverings of Echinoderms Spines Tube feet

Locomotion of Echinoderms Water vascular system: water filled sac (ampulla) pushes water into tube feet, suckers on tube feet help to attach and move.

Class Asteroidea (the class we are most familiar) Examples: sea stars Blue sea star

Class Asteroidea: Skeletal Structure Some ossicles have pedicellaria- pincer like structures which have muscles and nerves used for keeping animals off the surface of the sea star

Reproduction of Asteroidea Sexual reproduction, female can deposit up to 2.5 million eggs at one time Male and female

Symmetry of Asteroidea Five part radial symmetry Horned sea star

Unique Features of Asteroida Excellent predators: carnivores Have two stomachs, one goes inside the prey and begins to digest the food with enzymes(taking the stomach to the food!) One for digestion

Unique Features of Asteroida Regeneration of lost arms New sea star can be regenerated from one arm attached to central disk

Body Coverings of Asteroidea Hundreds of tube feet covering delicate skin Spiny skin: echino: spiny, derma: skin

Locomotion of Asteroidea TUBE FEET Used for grabbing food too

Class Ophiuroidea Examples: brittle stars, sea baskets Brittle star Sea baskets

Skeletal Structure of Ophiuroidea Slender branched arms break easily Can regenerate easily Black brittle star

Unique Features of Ophiuroidea Few are predators Many filter feeders No anus Shed arms to avoid predators Central disk location of all reproduction and digestion Serpent star

Body Coverings Skin filled with hard plates (ossicles) Some are spiny

Locomotion Long slender arms used as oars, like they are rowing, Do not have tube feet

Class Echinoidea Examples: sea urchins, sand dollars

Class Echinoidea: Skeletal Features Lack arms Hard fused endoskeleton with spines Group of sea urchins living together

Unique Features of Echinoidea Sharp teeth in mouth on underside of body

Unique Features of Echinoidea Spines provide protection Some spines have toxins to paralyze prey

Unique Features of Echinoidea Anal sac on top of sea urchin

Body coverings of Echinoidea Spines

Locomotion of Echinoidea Tube feet

Class Holothuroidea Examples: Sea cucumbers

Skeletal Structure of Sea Cucumbers Soft body Ossicles small not fused together

Reproduction of Sea Cucumbers Asexually and sexually Sperm and eggs released into water Larvae free swimming

Symmetry of Sea Cucumbers Bilateral

Unique Features of Sea Cucumbers Eject sticky filaments (part of respiratory system)when threatened or to ensare prey

Body coverings of sea cucumbers Tough leathery exterior Tentacles at mouth Some spines

Locomotion of Sea Cucumbers Tube feet

Phylum Chordata: Subphylum Urochordata Examples: Sea squirts, tunicates

Skeletal Structure of Tunicates In early stages of development: Deuterostomes with notochord (not a backbone, but rod for support) Have pharyngeal pouches – simple gills

Reproduction Hermaphrodites: have both eggs and sperm Release sperm into water for other tunicates to take in incurrent siphon Fertilized eggs released

Unique Features Free swimming larvae like tadpoles, have nerve cord, notochord and postanal tail to help them swim As adults sessile, filter feeders Cilia around incurrent siphon helps get food in, passes through pharyngeal slits Food filtered in stomach Undigested food passes through excurrent siphon

Unique Features Incurrent siphon Excurrent siphon Stomach Heart Tunic Reproductive organs Pharyngeal slits

Body Coverings Tough sac called tunic

Locomotion Free swimming as larvae, sessile as adults

Subphylum: Cephalochorda Examples: Lanclets

Skeletal Structure Look like fish but are not. Notochord helps support muscles for swimming

Reproduction Male and female sexual

Unique Features Spend most of time with mouths sticking out of mud Cilia around mouth draws water through mouth and pharynx out the pharyngeal slits.

Body Coverings and Locomotion Scaleless Notochord helps support muscles for swimming and burying in sand

GOOD WORK!!!!